Electricity & Gas Meters

At the time of writing, the methodology for EPC assessments of existing dwellings is RDSAP 10. A significant methodology overhaul from RDSAP to the Home Energy Model (HEM) is proposed for 2026. In addition, government consulations indicate future changes to the format of EPCs and minimum rating levels required for private rental properties. Methods for improving EPC ratings will therefore change in the future.

✓ Dual-rate meters are essential for correctly recording storage heaters

✓ Export-capable meters maximise the EPC benefit of solar PV

✓ Smart meters currently have little effect on the EPC rating

✓ RTS-controlled meters are now treated as single rate in RdSAP

✓ Meter photographs provide excellent documentary evidence

You may think your electricity and gas meters might have very little influence on your EPC rating.

Surprisingly, choosing the 'wrong' meter type in an EPC assessment can reduce the rating significantly for some properties.

Electricity and Gas meters measure the amount of fuel consumed in a property.

• Electricity is measured in kilowatt-hours (kWh), but
• Gas is measured in cubic metres (m³)

The quantity of gas used (m³) is converted to kWh using the industry standard formula (in the UK) as follows:

kWh = (m³ x Volume Correction Factor x Calorific Value) / 3.6

Where: Volume Correction Factor is 1.02264 and the Calorific Value is shown on your gas bill but is around 39 to 40 MJ/m³.

Dividing by 3.6 then converts from megajoules to kWh.

So this is how gas, although measured in cubic metres can have a cost associated with it in pence per kWh, in the same way as electricity.

The EPC assessment methodology assigns a cost in pence per kWh to fuels and these costs are applied in the calculation of the end rating.

Currently, domestic EPC ratings are a cost-based metric - they are indicative of the annual cost of running a property, normalised to the floor area.

They consider 'regulated' energy costs which include:

• Space Heating
• Water Heating
• Lighting
• Ventilation

Assumed occupancy models are used in working out how much fuel is used, and this ensures EPC ratings are about the property rather than the occupants and their preferences.

In addition, generation from solar PV offsets electricity usage and excess generation provides a further financial benefit, both of which are applied in the final stages of the calculation.

During an EPC assessment, an energy assessor will record the following information about the utility meters:

• Is the electricity meter a smart meter?
• Is the electricity meter single rate or dual rate?
• Is the electricity meter export capable?
• Is a mains gas supply present?
• Is the gas meter a smart meter?

This page is about these distinctions and how they can affect the EPC rating of an existing dwelling.

Most properties have a meter that charges electricity to the occupier at a fixed rate throughout the whole day, and this is referred to in EPC assessments as a single rate meter.

Any electricity consumed in the property is charged at this single rate and at the time of writing this is likely to be around 24 p/kWh.

This type of meter might typically be found in properties that have gas boilers, oil boilers, heat pumps and also simple peak rate electric panel heaters.

You'd may also expect to find hot water cylinders with single immersion heaters in this type of property as well.

Some heating systems, however, are designed to work on a dual-rate arrangement, whereby they consume cheaper electricity overnight to 'charge up', and the occupier utilises that stored heat during the day when the rate is more expensive.

Typically at the time of writing the rates may be 30p/kWh during the day and 13p/kWh at night.

The most common of these systems include:

• Night Storage Heaters
• Hot water cylinders with dual immersion heaters

During EPC assessments, assessors check the electricity meter to see if they can view details of dual rates, ie peak rate and and off-peak rate.

If they can, they record the presence of a dual rate meter. Otherwise, a single rate meter is recorded.

In all cases, photographs are taken of the meter, and it's display as evidence in case the assessment is audited.

If dual rate cannot be determined from the meter, but the occupant is able to supply an electricity bill showing dual rates then that can be used as evidence and a photograph of that will be taken as well.

Assessors will visually check your electricity meter and potentially like to see an electricity bill if they need to confirm the meter is 'dual-rate'.

This is an example of an older style dual-rate electricity meter, and the two rates with their separate readings are clearly visible. There is therefore no doubt at all that this would be classified as a dual rate meter.

This next example is of a modern smart electric meter, and the display here has been photographed on the rate 2 reading page, thus confirming it's a dual rate meter.

With some older dual-rate meters you may come across a separate device that switches the meter between the two rates. This for example is an old mechanical electrical timer switch:

There is also an old system you may occasionally come across called RTS, and if you still have such a system it's probably now no longer working. We'll touch on this in the next section.

If the assessor is still looking to confirm that electricity is being charged at high and low rates but perhaps is having difficulty locating the right menu item on a modern smart meter then they can use a recent electricity bill instead.

In the example above, electricity is clearly being charged at a high and low rate.

The radio teleswitch service is an old system that used a radio signal to switch certain dual rate electricity meters from peak to off-peak rate and back gain each day.

The signal was transmitted on longwave radio, specifically piggybacked onto the BBC Radio 4 AM signal.

RTS was introduced in the 1980s and after various postponements it's decommissioning started in June 2025.

If you still have an RTS controlled meter, it's highly likely the time switching feature has now stopped working, and you should seek to get it replaced as soon as you can.

Since 1st May 2025, if a radio tele-switch is present in a property, the meter will be recorded as a single rate meter in any new EPC assessment (Convention 9.13).

Some of these RTS controlled meters still remain in place so it's still possible to come across them from time to time.

There are some scenarios where a heating system is present that would normally require a dual-rate meter but where a single rate meter is present.

If storage heaters are present but there is only a single rate electricity meter then the heaters will only be recorded in an EPC assessment as standard electric panel heaters (Convention 4.2).

This will adversely affect the rating compared to that which would have been obtained if a dual rate meter had been present.

If a hot water cylinder is present with dual immersion heaters but there is only a single rate electric meter, the cylinder is entered as only having a single immersion (Convention 6.03).

Landlords and homeowners therefore might be interested in reviewing their electricity meter and heating arrangements to make sure an EPC assessment makes the best outcome for their property.

An export capable electricity meter is one that can measure the amount of imported and exported electricity.

Imported electricity is that which is consumed from the grid.

Exported electricity is that which flows in the opposite direction. This could for example be excess electricity generated by solar PV panels that is sent back to the grid.

An assessor will see if information can be displayed on the meter showing exported kWh. A photograph of this helps towards evidence for audit purposes.

'Export capable' would normally be assumed in the case of a smart meter anyway, but informaton on social media forums indicate that accrediation schemes may take different views.

On my electricity meter, a Kaifa MA120, if the meter had exported more than 1kWh of electricity there would be a '-A' reading, indicating kWh of exported electricity. That would be the ideal page to evidence export capability.

However, that page doesnt display on my meter because I don't have solar PV, and the meter was recently installed. The only menu item I have been able to locate relating to 'export' at the moment is the export maximum demand rate page, showing 0kW. The reference to 'export' on this page would be enough for any auditor to confirm the meter is 'export capable', even though it is a smart meter.

As an alternative, sight of the owners utility bill showing export information would also suffice.

The selection of an export capable electricity meter as opposed to one that is not export capable can affect an EPC certificate.

For example:

• If solar panels are present at a property but the electricity meter is not export capable then any excess PV generation modelled in an EPC assessment of the property will not be exported to grid and the EPC rating limited, sometimes significantly.
• If solar panels are not present at a propety and the electricity meter is not export capable, then if a Solar PV recommendation appears on the EPC, the improved rating associated with that recommendation will also be limited.

In a similar way, an export capable meter would also be expected where a wind turbine or small scale hydro system are present.

In the past, EPC assessments didn't record whether electricity or gas meters were smart-enabled.

The only information recorded was whether an electricity meter was single or dual rate and whether a mains gas supply was present.

Since the introduction of RDSAP 10 however, assessors now record whether smart meters are present.

Although smart meters currently have almost no influence on the headline EPC rating, they are likely to become increasingly important as the proposed Home Energy Model introduces additional metrics, including the Smart Readiness metric.

The textual content of the current EPC certificate does change slightly when smart meters are recorded so an error in getting this right could result in a failure if picked up at audit.

The top section of this electricity smart meter is the part that enables reporting back to the energy supplier. The row of LEDs is the key indicator, including ones labelled: HAN and WAN.

This gas meter is one of the early SMETS1 type smart meters. The keypad is the main indicator, but also notice 'HAN' on the LCD display.

If you have a meter that is not smart enabled, you can ask your energy supplier to replace it with one that is, and they are usually keen to do so.

Between 1 January 2022 and 31 December 2025, energy suppliers were required to meet binding annual targets for installing smart and advanced meters. This four-year obligation was designed to drive the rollout of smart metering across the country and has now concluded. As part of their responsibilities, suppliers needed to publicly share on their own websites:

• their annual installation target
• their performance against these targets

For 2026 and beyond, following recent government consultation, an update indicates policy moving forwards:

https://www.gov.uk/government/consultations/smart-metering-policy-framework-post-2025

'Mains gas supply available' is recorded in an EPC assessment if:

• There are mains-gas appliances in the property, or
• A gas meter is present

This is described in RdSAP Convention 8.02.

If 'mains gas available' is indicated in an assessment, recommendations may appear on an EPC to change non-gas heating and hot water supplies to gas-fired systems.

If 'mains gas available' is not indicated in the assessment, then those recommendations cannot be presented.

✓ The type of electricity meter can significantly affect an EPC rating in specific situations
✓ Dual-rate electricity meters should normally be recorded where storage heaters or dual-immersion cylinders are installed.
✓ Export-capable electricity meters allow export payment capability from Solar PV to be recognised in the EPC calculation.
✓ Photographs of electricity and gas meters provide valuable documentary evidence for an EPC assessment.
✓ Recent electricity bills can help confirm tariff details, meter type and export payments.
✓ Smart meters currently have little direct effect on EPC ratings, but this may change with future EPC reforms.
✓ Gas meters measure gas in cubic metres, but suppliers convert this into kilowatt-hours (kWh) for billing purposes.
✓ Correctly identifying the meter type helps ensure the EPC uses the most appropriate assumptions, resulting in a more accurate rating.

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